The present invention generally relates to portable hand-held power saws and more particularly to a cut guide for a portable hand-held power saw that permits the operator to easily and efficiently adjust the plumbness of the cut.
Many tradespersons, such as pipe fitters, steam fitters and electricians, routinely cut metal workpieces such as pipes, tubes and conduit with portable hand-held power saws. In some applications, such as when the end of a pipe or conduit is to be threaded, it is highly desirable that the cut be perpendicular to the axis of the workpiece so that the maximum axial deviation or runout of the cut is less than about one-thirty second of an inch. When this degree of accuracy is needed, the tradesperson was typically forced to employ a free-standing cutoff saw or a portable hand-held band saw. Free-standing cutoff saws, however, are not typically practical due to issues with their cost and size, as well as the free-standing (i.e., non-portable) nature of the saw.
Although portable hand-held band saws provided the tradesperson with an efficient yet portable means for cutting workpieces, these tools do not typically provide a desired level of accuracy in the plumbness of the cut, due to variables such as the squareness with which the tradesperson holds the tool relative to the workpiece and, more significantly, the set, sharpness and symmetry of the teeth of the saw blade. As those skilled in the art will appreciate, variances in the set, sharpness and symmetry of the teeth of the opposite sides of a band saw blade will cause the band saw blade to cut more heavily on one side or the other so that the path of the saw blade curves or wanders to one side. Furthermore, the sharpness and set of a given blade will vary asymmetrically as the band saw blade wears.
In view of the foregoing, a tradesperson typically employs a xe2x80x9cwrap-around gaugexe2x80x9d to mark the location of the cut around the full circumference of the workpiece when portable hand-held band saws are used. A wrap-around gauge is a flexible strip of material, usually cardboard, having a straight edge. The straight edge of the gauge is aligned to the desired location of the cut and thereafter wrapped around the circumference of the workpiece such that the straight edge is aligned to itself along its full length. The tradesperson then marks the location of the cut with a marker or pencil, using the straight edge of the guide as a reference. With the location of the cut thus marked, the tradesperson uses the portable hand-held band saw to partially cut through the workpiece. The workpiece is next rotated through a desired angle, such as about 90xc2x0 to about 180xc2x0 and the portable hand-held band saw is employed to cut through a second portion of the workpiece. The steps of rotating the workpiece and at least partially cutting through the workpiece are repeated until the cut through the workpiece has been completed. Needless to say, this method is not desirable, since it is relatively inefficient and cumbersome, and does not guarantee the desired level of accuracy.
Accordingly, there remains a need in the art for an improved cut guide that can be used in conjunction with a portable hand-held band saw.
In one preferred form, the present invention provides a cut guide for a portable hand-held saw that has a blade with a cutting portion that is disposed along a generally vertical axis. The cut guide includes a mounting portion, which is configured to be coupled to the saw, a guide block portion, a guide portion and an adjustment mechanism. The guide block portion, which defines a generally vertical cutting stroke axis, is pivotally coupled to the mounting portion such that the cutting stroke axis can be pivoted relative to the cutting portion of the blade. The guide portion is movably coupled to the guide block portion along the cutting stroke axis. The guide portion includes an abutment structure with at least one feature for establishing an orientation of the cutting stroke axis relative to a longitudinal axis of a workpiece. The adjustment mechanism pivots the guide block portion relative to the mounting portion to thereby adjust an angular relationship of the cutting stroke axis relative to the longitudinal axis of the workpiece.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.